1. Field of the Invention
The present invention relates to a method and apparatus for collecting cancer or other cells present in urine and other body fluids for microscopic examination for diagnostic or therapy purposes.
2. Description of the Prior Art
Urine, saliva, sputum and uterine secretions and other such fluids for testing are forced under pressure through a filter that consists of a plastic film some 10 .mu.m thick evenly perforated with substantially round holes about 5 .mu.m in diameter. The liquid portion of the body fluid passes through the perforations while the object specimen cells are retained on the plastic film. Concentrated body fluids are suitably diluted before filtration.
When the cells on the film are stained and examined under the microscope, if cancer cells are found the diagnosis is that cancer is present where the fluid was secreted. The method is not limited to cancer cells, and can be effectively applied to diagnoses relating to the whole range of body fluid components. In recent years, some major hospitals that have instituted this method have reported a high rate of cancer discovery.
FIG. 12 is a side cross-sectional view of an arrangement of a conventional apparatus for obtaining medical test specimens, FIG. 13 is a perspective view of a conventional specimen collection element, and FIG. 14 is a side view of a plurality of specimen collection elements, each consisting of a lower support member and an upper support member, arranged on a suction apparatus.
In the drawings, reference numeral 1 denotes a known specimen collection element comprised of a thin, stiff plate 2 with a round hole 2a at its center, and a plastic film 3 attached on the plate 2 so that the hole 2a is covered. Reference number 4 represents a lower support member which, with an upper support member 5, provides airtight support for the specimen collection element 1. The top of the lower support member 4 is open and the base has a projection 4a which has a passage 4aa. The upper support member 5 is basically cylindrical in shape and is provided on its lower surface with a packing 6 for pressure contact with the plate 2 around the hole 2a. Peripheral welding or the like is used to attach the lower support member 4 and upper support member 5 together to thereby hold the specimen collection element 1. A syringe 7 is connected to the projection 4a of the lower support member 4 by a tube 8. A suction pump 9 is provided to pump air out via the passage 4aa. L denotes the body fluid being tested.
The specimen collection process will now be described. To collect test specimens from the body fluid L, the body fluid L is put into the upper support member 5. When the syringe 7 is used to create a negative pressure in the lower support member 4 via the tube 8, the liquid portion of the body fluid L passes from the upper support member 5 through the plastic film 3 and into the syringe 7, whereby the human cells are captured on the plastic film 3.
When there is no more body fluid L in the upper support member 5 or when the pores of the plastic film 3 become clogged with cells, preventing the passage of any more of the body fluid L, the lower support member 4 and upper support member 5 are opened and the plastic film 3 is removed and stained for microscopic examination. For simultaneous collection of multiple sets of specimens, the configuration of FIG. 14 can be used in which a plurality of specimen collection units, each consisting of a lower support member 4 and an upper support member 5, are arranged on a suction pump 9.
FIG. 15 is a side cross-sectional view of an another arrangement of a conventional apparatus for obtaining medical test specimens. Parts corresponding to those in the arrangements of FIGS. 12 to 14 have been given the same reference numerals, and further explanation thereof indicates omitted. In FIG. 15, reference numeral 10 is a cup into which the body fluid L represents placed, and 11 is a lid for the cup 10. The lid 11 is provided with a vent 11b and a hole 11a for the insertion of a tube 12 that reaches to the bottom of the cup 10.
Reference number 13 denotes a lower support member that has an open top and is provided in its base with a projection 13a with a passage 13aa that connects to the upper end of the tube 12. The upper inner surface of the lower support member 13 has a female thread. Reference number 14 denotes an upper support member which is provided on its outer surface with a male thread for engaging with the female thread of the lower support member 13, and a centrally located passage 14a that is connected to the syringe 7. By screwing the upper support member 14 into the lower support member 13, the specimen collection element 1 is held in an airtight state.
The specimen collection process will now be described. To collect test specimens from the body fluid L, the body fluid L is put into the cup 10, the lid 11 is closed and the tube 12 is inserted via the hole 11a into the cup 10 until the tube reaches the bottom of the cup 10. The syringe 7 connected to the passage 14a of the upper support member 14 is used to exert a negative pressure to draw the liquid portion of the body fluid L up through the tube 12 and lower support member 13 and into the syringe 7, whereby the cells in the fluid are captured on the plastic film 3.
When there is no more body fluid L in the cup 10 or when the pores of the plastic film 3 become clogged with cells, preventing the passage of any more of the body fluid L, the lower support member 13 and upper support member 14 are opened and the plastic film 3 is removed and stained for microscopic examination. For simultaneous collection of multiple sets of specimens, the configuration of FIG. 14 can be used in which a plurality of specimen collection assemblies each consisting of a cup 10, a lower support member 13 and an upper support member 14, are arranged on a suction pump 9.
In the case of the conventional specimen collection devices described above, when the lower support member 4 (or lower support member 13) and upper support member 5 (or upper support member 14) are opened after completion of the cell collection process, the remaining body fluid L sticks to the fingers and splashes around, which is unsanitary. In addition to this, when the syringe 7 (or suction pump 9) is detached from the tube 8 (or upper support member 14) to dispose of the body fluid L, the hands of the personnel holding the syringe are contaminated by the body fluid L. As the body fluid L may contain harmful bacteria, viruses, toxic substances and the like, it is necessary to sterilize the tube 8 and syringe 7 (suction pump 9) that are frequently touched by hands during specimen collection.
However, perfect sterilization of the personnel and equipment involved has a highly adverse affect on the efficiency of testing procedures, and sterilization that is less than complete can give rise to health risks. Moreover, microscopic examination can only take place after the plastic film 3 has been stained, put on a slide and covered with a cover glass, while if it is to be kept as a sample preparation it has to be sealed, but the specimen collection element 1 is not suitable for such procedures.
Also, it is important to apply the right amount of pressure to the lower support member 13. Too little pressure will result in insufficient filtration, while too much pressure will cause deformation of cells into the holes of the plastic film 3, giving rise to diagnostic errors, so the pressure has to be maintained at an appropriate level at all times. However, even slight changes in the volume of the suction pump 9 can cause major changes in the suction pressure applied to the non-compressible body fluid L, making it difficult to constantly maintain the required pressure, which fluctuates sharply between 0/cm.sup.2 and around 1/cm.sup.2, squeezing the cells into the holes of the plastic film 3 and making diagnosis difficult.
An object of the present invention is to provide a method and apparatus for collecting medical test specimens whereby cells can be collected without damaging them and the cleanliness of parts frequently touched by hand during the specimen collection process can be maintained, with none of the fluid being processed adhering to fingers or being splashed around.